Mechanism in a sewing machine for enlarging loop of the upper thread for the purpose of performing zig-zag stitching



June 1961 BUNSAKU TAKETOMI 2,989,017

MECHANISM IN A SEWING MACHINE FOR ENLARGING LOOP OF THE UPPER THREAD FOR THE PURPOSE OF PERFORMING ZIG-ZAG STITCHING Filed Oct. 23, 1957 3 Sheets-Sheet 1 J 1961 BUNSAKU TAKETOMI 2,989,017

MECHANISM IN A SEWING MACHINE FOR ENLARGING LOOP OF THE UPPER THREAD FOR THE PURPOSE OF PERFORMING ZIG-ZAG STITCHING Filed Oct. 23, 1957 3 Sheets-Sheet 2 4 24 Fig.6

gill

"mum Fig: I 46, 5/! 40 J 0, 1951 BUNSAKU TAKETOMI MECHANISM! IN A SEWING MACHINE FOR ENLARGING LOOP OF THREAD FOR THE PURPOSE OF PERFORMING ZIG-ZAG STITCI-IING Filed Oct. 25, 1957 FIG. 20

United? States. Patent 2,989 017 I MECHANISM IN A SEWING MACHINE FOR- EN- "LARGING LOOP OF THE UPPER THREAD FOR THE PURPOSE OF PERFORMING ZIG-ZAG STIT-CI-IING Bunsaku Taketomi, 9 Uchiyama-cho Z-chome Chigusa-ku,

Nagoya, Japan Filed Oct. 23, 1957, Ser. No. 691,967 Claims priority, application Japan Oct. 29, 1956 1 Claim. (Cl. 112-187) This invention relates to a sewing machine, and more particularly to a mechanism for enlarging a loop of the upper thread, with the aid of which and a displaceable needle it is possible to perform zig-zag stitches and embroideries, without materially changing the construction of the existing type of vertical shuttle of a horizontally reciprocal or revolving type having a stationary shuttle race, the shuttle being adapted exclusively for performing straight stitches.

In a sewing machine, it is so arranged that the nose of the shuttle is inserted into and adapted to catch the loop of the upper thread formed at the beginning of the upward movement of the needle and to be moved around the bobbin case. As said loop of the upper thread is relatively small, the shuttle must be arranged in such a manner that the nose thereof is moved in a path which is in close proximity of the needle. With respect to the shuttle with an immovable shuttle race when the needle is displaced from the path of the shuttle nose for a distance of about mm. or more for the purpose of zig-zag stitching, the loop of the upper thread is beyond the reach of the shuttle nose, so that zig-zag stitching could not be performed at all. According to this invention, means is provided for positively enlarging said loop of the loosened upper thread to obtain a wider loop adapted to be accurately caught by the nose of the shuttle. By such means, it is possible to perform zig-zag stitching as well as straight stitching, without necessitating the provision of rockable shuttle race.

One of the objects of the invention is to provide a mechanism adapted to enlarge a loop of the upper thread to permit the zig-zag stitches without necessitating the provision of a specially designed shuttle and shuttle race and actuating means therefor adapted for zgig-zag stitch- Another object of the invention is to provide a mechanism for enlarging a loop of the upper thread, permitting zig-zag stitches employing an existing type of stationary shuttle race as used in a variety of sewing machines for household use, whereby avoiding any vibration of the sewing machine and parts thereof caused by the provision of a rockable shuttle race or a horizontal shuttle with the actuating mechanism therefor, which being usually employed'in the zig-zag sewing machines.

A further object is to provide such mechanism which is simple in construction, economical to manufacture, can readily be assembled, and is reliable in operation.

Other or further objects of the invention will be obvious upon an understanding of the illustrative embodiments about to be described, or will be indicated in the appended claim, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In the accompanying drawings, in which several embodiments of the invention are illustrated:

FIGURE 1 is a front view of a shuttle race of a sewing machine equipped with a mechanism according to this invention; v I I FIGURE 2 is a perspective view of the mechanism;

FIGURE 3 is another perspective view showing the shuttle, needle, upper thread, and loop enlarging lever in an operated position;

FIGURE 4 is a plan view in somewhat enlarged scale of said loop enlarging lever and illustrating. needle displacement;

FIGURE 5 is a side view thereof showing the upper thread with its loop enlarged;

FIGURE 6 is a plan view showing in an enlarged scale a needle having an eye arranged obliquely relative to and as compared with that of the ordinary needle.

FIGURE 7 is a front view of the shuttle race equipped with a modified form of the mechanism according to this invention;

FIGURE 8 shows a side view thereof partly in section;

FIGURE 9 is a plan view thereof;

FIGURE 10 is a perspective view of the mechanism with a part removed;

FIGURE 11 is a front view of the shuttle race equipped with a further modified form of the mechanism according to this invention;

FIGURE 12 is a plan view thereof;

FIGURE 13 shows a front view of the shuttle, partly in section, showing a modified design of the bobbin case and the shuttle;

FIGURE '14 is a perspective view of the mechanism with a part removed;

FIGURE 15 is a plan view showing the relative position of the loop enlarging lever and the needles when the mechanism according to this invention is applied to so-called three needle stitching.

FIGURE 16 is a front view of the shuttle race equipped with a still further modified form of the mechanism according to this invention;

FIGURE 17 shows a side view thereof, partly in section;

FIGURE 18 is a plan view of the hook plate forming the loop enlarging lever as used in the last mentioned form of invention;

FIGURE 19 is a perspective view of the modified construction of a connection forming a part of the mechanism for actuating the loop enlarging lever, and

FIGURE 20 is a partially section perspective view of a zig-zag stitching head and shuttle race with which the invention may be used.

Referring to the embodiment shown in the drawings, FIGURESI to 6, the reference numeral 1 designates a stationary shuttle race, in which there is a shuttle 2 having a hook or nose 2'. 3 designates the loop of the upper thread formed at the beginning of the upward motion of the needle 4. '5 is a shuttle race top spring. 6 is a feed dog, and 7 is a needle plate. 8 designates the fabrics to be sewed. 9 is a part of a bed. The above mentioned parts of the sewing machine are not shown or described in detail, as they form no part of the present invention.

According to this invention, a lever '10 is pivotally mounted by means of a stud screw 11 on the under side of the bed 9. To one end of said lever 10 is secured. a hook plate 12 forming a loop enlarging lever and having ahook 12 which extends in close proximity of the needle 4. As shown in FIGURE 2, a cam 13 is mounted on the lower shaft 14 for driving the shuttle. A lever 15 pivotally mounted to the bed as at 16 has a roller 17 which abuts against the cam face 13 of the cam 13, the lever 15 being biased by means of a spring 18. lThe other end of the lever 10 and the free end of the lever 15 are connected by means of a link 19. Said cam 13 is so designed that according to the rotation of the lower shaft '14 the levers 15 and 10 are oscillated for angles of P and P respectively.

Referring now to FIGURE 4, assume that zig-zag stitching of the width P is desired. The needle 4 is kept apart from the nose or hook 2 of the shuttle for about 5 mm. When the needle 4 is lifted, the upper thread being loosened is formed into a loop 3, and immediately thereafter the lever is swung clockwise around the pivot 11, and the free end or hook 12' of the plate 12 will be inserted into said enlarged loop 3 and it pulls the loop forming thread outwardly, thereby enlarging the size of the loop, bringing it into the path of the nose 2' of the shuttle, as shown in FIGURES 2, 3 and 5. Then, the above mentioned parts are returned to their initial position by the action of the spring 18 under the control of the cam 13. In such manner, the cycle of operation of the above mentioned loop enlarging mechanism is repeated.

In order that the hook plate 12 may catch the enlarged loop 3 without fail, it would be desirable that the needle 4 is mounted to the needle bar with the eye arranged obliquely at an angle of about 45, as shown in FIGURE 6. If the eye of the needle were arranged at right angle to the direction of movement of the shuttle 2, the loop of the upper thread would be extended similarly in the direction of the movement of the shuttle, and the hook 12' of the hook plate 12 may fail to enter the loop. The oblique arrangement of the eye of the needle is to remove such disadvantage. For the purpose, the stem or root portion of the needle may be cut as at 4 in the direction oblique to the eye 20, as shown in FIGURE 6. Or, alternatively, a needle having the root portion of a circular cross section may be used and clamped to the needle bar so as to bring the eye in the oblique position as desired.

It is to be noted that the above mentioned lever 10 with the hook plate 12, the lever 15 and the link 19 are made of relatively thin sheet metal and are so light that the momentum of said parts is extremely small as compared with the mechanism in the existing zig-zag sewing machines, whilst in the latter it is designed so as to move the shuttle race including the shuttle, bobbin and bobbin case, the shuttle driving shaft, a vertical shaft and other parts pertaining thereto for the purpose of performing zig-zag stitching.

In the modified form of the invention as shown in FIG- URES 7 to 10, the righthand upper portion of the shuttle race 1 is formed of a shoulder 21, upon which a stud 22 is secured. A hook plate 23 having a vertical sleeve 24 is pivotally mounted on said stud 22 for swinging motion as shown by arrow A-A in FIGURE 10. Said hook plate 23 forming the loop enlarging lever is so arranged that its free end forming a hook 23 is moved in a path in close proximity of the needle 4. A coil spring 25 is wound around the sleeve 24, so that the hook plate 23 is normally urged to return to the initial position as shown in FIGURE 9.

Bearing 26 is for a horizontal axle 27, and is mounted by screwing into a horizontal internally threaded hole bored through the righthand lower portion of the shuttle race 1 as viewed in FIGURE 7. At one end of said axle 27 is secured a cam controlled arm 28. 29 is an arm secured to the other end of said pin 27 and extending upwardly on the outer side of the shuttle race 1. The upper free end of said arm 29 abuts against a projection 30 which projects from the sleeve 24 at right angle to the hook plate 23. 31 is a cam mounted to and around the boss of the driver 32 for driving the shuttle. The cam 31 is adjustably mounted by means of a screw 33. The arm 28 is held in engagement with the cam 31 by being urged by the spring 34. 35 designates a portion of the lower shaft of the sewing machine.

As in the existing sewing machine for household use, the lower shaft 34 partakes a reciprocal rotation and the similar rotation is given to the shuttle in the shuttle race 1. According to the embodiment shown, by the provision of the cam 31 and the arm 28 controlled thereby, the upper end of the vertical arm 29 will be swung in the direction of arrows B-B, thereby pushing the projection 30 to actuate the hook plate 23 in the direction of arrow A-A as shown in FIGURE 10. The amplitude of the swing motion of said hook plate 23 may be adjusted, When the amplitude of the swing of the needle for zig-zag stitching is 4 mm., it may be so designed that the free end of the hook plate 23 is moved for the amplitude of about 8 mm. Such amplified movement of the hook plate 23 may be obtained by determining the leverage of the arms 28 and 29 relative to the eccentricity of the cam 31.

Immediately after the needle 4 begins to be lifted from its lowermost position and there has been formed a loop of the upper thread, the driver 32 is rotated so that the arm 28 controlled by the cam 31 is swung around the axis 27, whereby the hook plate 23 is actuated and swung inwardly through the action of the vertical arm 29 and the projection 30, bringing the hooked end 23 of the hook plate into engagement with the loop immediately before the nose 36 arrives to the loop. Thus, the loop is pulled and enlarged in the direction of arrow B in FIG- URE 9, so that the nose 36 of the shuttle can readily catch the loop in running around the bobbin case.

In the embodiment shown in FIGURES 11 to 15, the axle 41 of the cam controlled arm 42 is mounted in a hole provided in the lefthand lower portion of the shuttle race 1, as viewed in FIGURE 11, instead of the right hand upper portion of the shuttle race as in the embodiment shown in FIGURES 7 to 10. The free end of the said arm 42 is engaged by a cam 43 mounted to the boss of the driver 44. The upper free end of the vertical arm 44 secured to the outer end of the axis 41 is in engagement with a' forked projection 45 of the hook plate 46 having a hooked end 46. The arrangement of the other parts illustrated being substantially same as in the former embodiment, no further description will be necessary,

In the existing zig-zag sewing machine, the axis of oscillation of the needle bar is customarily located at a point distant from the needle bar, for instance, at a point in the presser bar or farther therefrom. In other words, the width of the zig-zag stitching is varied within the range determined by the oscillating motion of the needle bar along the are having its center located in the presser bar. Whereas, in the former embodiment shown in FIGURES 7 to 10 in which the hook plate 23 is oscillated about the axis 22 located at the righthand upper portion of the shuttle race 1, the arc of the motion of the hooked end 23' will be just reversed to the said are of oscillating motion of the needle 4. Hence, it results that the distance between the hooked end 23' of the hook plate 23 and the needle 4 becomes larger as the amplitude of the oscillation of the needle, i.e. the width of the zigzag stitches increased. This is, disadvantageous in practical use. To remove such disadvantage, in the embodiment shown in FIGURES 11 to 15, the axle 22 of the hook plate 46 is located in the left portion of the shuttle race 1 as viewed in FIGURE 11, so that the curvature of the arc of oscillating motion of the hook plate 46 is in the same direction of the curvature of the arc of the oscillating motion of the needle. In this case, however, it will be necmsary that the position of an eye piece 47 of the bobbin case 48 shall be displaced rightwardly for an angle of 0 from the normal position, and that the stopper 49 on the shuttle shall likewise be transferred from left to right on the shuttle, as shown in FIGURE 13. According to the embodiment shown, so-called two or three needles stitching may be performed. In FIGURE 15, illustrating the application of the three needles stitching, 4, 4' and 4" are the needles, and 3, 3 and 3" designate the loops formed by said three needles, respectively. In each needle, the eye is obliquely arranged at an angle of about 40. In this form of invention, the hooked end of the hook plate 46 will catch all three loops to enlarge them.

In the embodiment shown in FIGURES 16 to 18, an axle 51 is journalled in a bearing 52 provided in the left lower portion of the shuttle race 1 and has at its inner end an arm 53 abutting against the cam 54 mounted on the boss of the driver in the similar manner as in the former embodiments, To the outer end of said axis 51 is secured the lower end of the vertical arm 55 consisting of a thin sheet metal, and securely connected to the upper end thereof is a pin 56. This pin 56 is slidably inserted through a diametrical bore in a ball 57. Said ball 57 is embraced by two semi-spherical'cups 58 and 59 which form an extension of the hook plate 60 which is formed as a bell crank having its pivot 61, said ball and the cups 58 and 59 constituting a swivel joint. The hook plate 60 is securely mounted to a sleeve 62 which is loosely mounted on the pivot 61. Each of the semi-spherical cups 58 and 59 is provided in its central portion with an opening somewhat larger than the pin 56.

In operation, the vertical arm 55 is swung upon the reciprocating rotation of the cam 54, thereby the hook plate 60 will be oscillated in a horizontal plane with an amplified movement. The arm 55 being made of thin sheet metal having resiliency, the arcuate movement of the pin 56 is permitted. On the other hand, due to the provision of said ball-and-cup connection any backlash may be avoided in the driving connection between the pin 56 and the hook plate 60.

In FIGURE 19, a modified form of the connection between the axle 51 and the vertical arm 55 is shown. In this modification, instead of using resilient sheet metal arm 55 a long pin 56 is used, and the lower end thereof is connected with the outer end of the axle 51 through a joint consisting of a U-shaped guide block 70 secured to the outer end of the axis 51, a bearing block 71 having a central longitudinal bore, through which the lower end of the pin 56' is slidably inserted, said bearing block 71 being pivotally mounted to the guide block 70 as by means of a pivot 72.

FIGURE 20 illustrates a zig-zag stitching head 74 such as may be used with the invention.

What I claim is:

In a sewing machine having a zig-zag stitching head, improved means for performing zig-zag stitching comprising a needle mounted to reciprocate vertically and to be alternately displaced horizontally for forming vertical thread loops extending horizontally in a common vertical plane at the positions of farthest needle advance in reciprocation, a stationary shuttle race mounted vertically 6 adjacent and below said needle and transverse to the horizontal displacement of said needle, a shuttle mounted to rotate in said stationary race for successively intersecting said thread loops as they are formed, and thread loop positioning means for extending said thread loops horizontally and comprising a cam means fixed to rotate with said shuttle, a shaft journaled in said shuttle race, a first arm fixed on said shaft and operatively engaging said cam to rotate said shaft, a second arm normal to said first arm and fixed on said shaft at one end and mounting a pin on the other end for swinging about said shaft as it is rotated, a ball diametrically pierced mounted on said pin, a light-weight hook plate shaped as a bell crank and pivoted at the bell crank angle to said shuttle race, the hook plate terminating at the free end in a thread loop engaging hook and at the other end in two hemispherical cups, each having a center opening, said cups cooperating with said ball to form a swivel joint and being held in 000p eration by said pin engaging in said center openings, whereby the swinging of said second arm about said shaft causes the bell crank hook plate to rotate about its pivot which is adapted to swing the hook at the free end of the hook plate transversely to the vertical plane of said thread loops and parallel to the horizontal displacement of the needle to engage said thread loops and extend them horizontally of the needle to engage said thread loops and extend them horizontally of said needle.

References Cited in the file of this patent UNITED STATES PATENTS 13,727 Langdon Oct. 30, 1855 896,137 Mills Aug. 18, 1908 1,049,430 Wilkes June, 7, 1913 1,158,937 Krautsch Nov. 2, 1915 1,283,437 Williams Oct. 29, 1918 1,310,460 Williams July 22, 1919 1,595,245 Rader Aug. 10, 1926 FOREIGN PATENTS 356,504 France Oct. 7, 1905 

